Thermodynamic Dissection of the Intrinsically Disordered N-terminal Domain of Human Glucocorticoid Receptor
Thermodynamic Dissection of the Intrinsically Disordered N-terminal Domain of Human Glucocorticoid Receptor
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DOI：
10.1074/jbc.m112.355651
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发表时间：
2012-08-03
影响因子：
4.8
通讯作者：
Hilser, Vincent J.
中科院分区：
文献类型：
--
作者：
Li, Jing;Motlagh, Hesam N.;Hilser, Vincent J.
内在无序（ID）序列片段在细胞信号蛋白和转录因子中含量丰富。由于ID区通常折叠作为其细胞内功能的一部分，因此了解折叠状态以及未展开和折叠状态之间的转换至关重要。具体来说，重要的是确定1)大的ID片段是否包含不同的热力学和/或功能不同的区域，2)是否有任何ID区域在激活时折叠，3)不同ID区域之间的耦合程度，以及4)ID结构域的稳定性是否是功能的决定因素。在这项研究中，我们对人糖皮质激素受体（GR）的全长ID n端结构域（NTD）及其两种自然存在的翻译异构体进行了热力学表征。利用保护性渗透物三甲胺n -氧化物（TMAO）诱导折叠转变。发现三种NTD亚型中的每一种都经历了一个合作折叠转变，从热力学上看（基于m值）与类似大小的球状蛋白无法区分。NTD异构体的外推稳定性与其对应的GR翻译异构体的已知活性有明显的相关性。数据表明，全长NTD至少具有两个热力学耦合区，一个是GR转录活性不可或缺的功能区，另一个是调控区。其长度用于调节NTD的稳定性，从而调节GR的活性。这些结果提示了一种新的功能范式，即类固醇激素受体特别是ID蛋白一般可以具有多个功能不同的ID区域，这些区域相互作用并调节重要功能位点的稳定性。
Intrinsically disordered (ID) sequence segments are abundant in cell signaling proteins and transcription factors. Because ID regions commonly fold as part of their intracellular function, it is crucial to understand the folded states as well as the transitions between the unfolded and folded states. Specifically, it is important to determine 1) whether large ID segments contain different thermodynamically and/or functionally distinct regions, 2) whether any ID regions fold upon activation, 3) the degree of coupling between the different ID regions, and 4) whether the stability of ID domains is a determinant of function. In this study, we thermodynamically characterized the full-length ID N-terminal domain (NTD) of human glucocorticoid receptor (GR) and two of its naturally occurring translational isoforms. The protective osmolyte trimethylamine N-oxide (TMAO) was used to induce folding transitions. Each of the three NTD isoforms was found to undergo a cooperative folding transition that is thermodynamically indistinguishable (based on m-values) from that of a globular protein of similar size. The extrapolated stabilities for the NTD isoforms showed clear correlation with the known activities of their corresponding GR translational isoforms. The data reveal that the full-length NTD can be viewed as having at least two thermodynamically coupled regions, a functional region, which is indispensable for GR transcriptional activity, and a regulatory region, the length of which serves to regulate the stability of NTD and thus the activity of GR. These results suggest a new functional paradigm whereby steroid hormone receptors in particular and ID proteins in general can have multiple functionally distinct ID regions that interact and modulate the stability of important functional sites.